1. Field of the Invention
Example embodiments of the invention relate to a virtual desktop infrastructure (VDI) system, and more specifically, to a system and method for providing a virtual desktop service using a cache server in which each host server group having at least one host server includes a cache server, and the cache server uses physically separate caches to perform a read process and a write process, performs data prefetch or preread on a read cache on which a read process is performed when an overload occurs, and moves data in a write cache to a distributed file system so as not to degrade performance of the write cache according to an available space of the write cache on which a write process is performed.
2. Discussion of Related Art
In a VDI system for supporting a virtual desktop service, a storage connected to a central server backend systematically stores and manages an OS and applications used by users, and data generated by the users, and the users access the system remotely and perform necessary tasks as if it were their own desktop environment.
This VDI system may correspond to security such as information leakage prevention and intensive resource management. On the other hand, the VDI system has a problem in that response performance of the system affecting the user needs to be supported as in a personal PC. In particular, operations such as a simultaneous virus scan and a boot and login storm that is generated when most of the VDI system users start their tasks may cause a load of about 10 times that of a normal state. It is necessary to design the system so as to guarantee system response in such a case.
As expected, input and output operations with the storage are frequently required in the VDI system, which is the biggest cause of bottlenecks.
A structure of a general VDI system includes client terminals that are shown as a screen to a user, host servers having many VMs installed and operated therein, and a file system in which data for all VMs is stored. In order to accommodate an increase in data usage for the user and an increase of the number of virtual desktop users, the file system needs to support high scalability as an important characteristic. A storage area network (SAN) storage that is currently commonly used is very expensive and has limitations in terms of storage scalability.
The cost limitation may be overcome when network attached storage (NAS) is used. The NAS has many advantages but has relatively low response performance, and thus devices for overcoming the low response performance are necessary.
As described above and can be seen in many analysis results of a VDI workload characteristic, a VDI I/O workload is mostly caused by a small-sized random write, and is known to be about 80%. When a certain degree of bandwidth is supported in an environment having this characteristic, it is possible to achieve a satisfactory level of experienced performance of the entire VDI system by introducing a structure for improving write response performance.
Currently, in order to address these problems, a multi-level cache structure using a memory, an SSD, or the like has been proposed. In addition, a method for improving performance through providing a cache in the host server has been proposed. These methods may improve general-purpose cache performance but may not be optimal methods in which the VDI characteristic is reflected.